The present invention relates generally to sensors for detecting chemical changes in the ambient environment.
Chemical sensing and identification apparatus are implemented in many diverse fields. Automobile manufacturers use chemical sensors for measuring air/fuel ratios and intend to use sensors to measure pollutant emissions, alternative fuel quality and build-up of volatile chemicals such as hydrogen in battery-operated vehicles. Environmental testing firms and industries required to meet Federal Air Quality Standards and workplace safety standards use sensors to detect contaminant concentrations, toxic vapors and the distribution of pollutants in process control systems. Biomedical sensors are used to monitor concentrations of glucose, blood gases and other constituents in the blood and for detecting analytes such as hormones and toxins.
Existing sensors have proven inadequate. Existing sensors do not meet requirements of cost, accuracy, precision and instrument size necessary in many applications. Electrochemical sensors require reference channels, are prone to drift and have considerable accuracy and cost restraints. Acoustic sensors are currently under development but suffer from problems related to high excitation frequencies and lack of selectivity. Optical sensors are suitable for a wide range of applications. Unfortunately, the most sensitive optical methods can require costly coupling and interconnect components that reduce the range of suitable applications for which optical sensors may be an attractive option.
Needs exist for chemical sensors with high sensitivity, precision and amenability to low-cost production methods for use in environmental monitoring, in process control and in biomedical analysis.